Thermal properties and shrinkage-swelling characteristic of clay soil in a tropical paddy field
2008
Ardiansyah.(Tokyo Univ. (Japan)) | Shiozawa, S. | Nishida, K.
Thermal conductivity (K) as functions of water content (w) is not so well known for swelling soils as that for non-swelling soils. We measured K and thermal diffusivity of a swelling soil taken from paddy fields in Indonesia, together with its shrinkage-swelling characteristic. The soil showed remarkable shrinkage-swelling nature ; void ratio of the soil in-situ exceeded 2.0 when flooded condition whereas it became less then 1.0 when the soil was dry. Observed K increased from 0.60 to 1.28 W/m/K with w increased from zero to 0.24g/g. However, for w greater than 0.24 g/g, K decreased gradually with increase in w, differently from non-swelling soil that shows monotonic K increase with w. The decrease in K with increase in w must be produced by increased void ratio. As a result, the value of K for the soil of most dry condition in the field (K=0.99 W/m/K) was almost the same as the value of K for flooded condition. Consequently, drying of the swelling soil has no effects of reducing heat conduction from surface into the soil when it is exposed to sunshine.
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